<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{
            width: 100px;
            height: 100px;
            border: 5px solid red;
            /*设置圆角 值越大越圆
            超过宽高一半为圆形*/
            border-radius: 2px;
            /*给元素添加内边距会影响元素的宽高*/
            padding-left: 100px;
            padding-top: 100px;
        }
    </style>
</head>
<body>
<div>边框测试</div>
</body>
</html>